Transformation | Compute rigid transformation and similarity transformation | 3D Printing library
kandi X-RAY | Transformation Summary
kandi X-RAY | Transformation Summary
This is a c++ library estimate 2 point sets's transformation, both for rigid transformation and similarity transformation. "Eigen3" is required for this library. Please install "Eigen3" before compiling this library. The reference documents are in folder "/reference".
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Trending Discussions on Transformation
QUESTION
I have source (src
) image(s) I wish to align to a destination (dst
) image using an Affine Transformation whilst retaining the full extent of both images during alignment (even the non-overlapping areas).
I am already able to calculate the Affine Transformation rotation and offset matrix, which I feed to scipy.ndimage.interpolate.affine_transform
to recover the dst
-aligned src
image.
The problem is that, when the images are not fuly overlapping, the resultant image is cropped to only the common footprint of the two images. What I need is the full extent of both images, placed on the same pixel coordinate system. This question is almost a duplicate of this one - and the excellent answer and repository there provides this functionality for OpenCV transformations. I unfortunately need this for scipy
's implementation.
Much too late, after repeatedly hitting a brick wall trying to translate the above question's answer to scipy
, I came across this issue and subsequently followed to this question. The latter question did give some insight into the wonderful world of scipy
's affine transformation, but I have as yet been unable to crack my particular needs.
The transformations from src
to dst
can have translations and rotation. I can get translations only working (an example is shown below) and I can get rotations only working (largely hacking around the below and taking inspiration from the use of the reshape
argument in scipy.ndimage.interpolation.rotate
). However, I am getting thoroughly lost combining the two. I have tried to calculate what should be the correct offset
(see this question's answers again), but I can't get it working in all scenarios.
Translation-only working example of padded affine transformation, which follows largely this repo, explained in this answer:
...ANSWER
Answered 2022-Mar-22 at 16:44If you have two images that are similar (or the same) and you want to align them, you can do it using both functions rotate and shift :
QUESTION
I have a data frame which I need to transform. I need to change the unique rows into single columns based on the value of a column.
My data below:
...ANSWER
Answered 2022-Mar-17 at 18:58Here is one method with data.table
- convert to data.table
(setDT
), make sure that the 'V3' is numeric
(for division - it was created as character), grouped by 'V1', create the 'transport' by extracting the 'V3' value where 'V2' is 'transport' and divide by the number of elements in 'V2' that are not "transport", then subset the data by removing the 'transport' elements from 'V2'
QUESTION
I am working on a large Pandas DataFrame which needs to be converted into dictionaries before being processed by another API.
The required dictionaries can be generated by calling the .to_dict(orient='records')
method. As stated in the docs, the returned value depends on the orient
option:
Returns: dict, list or collections.abc.Mapping
Return a collections.abc.Mapping object representing the DataFrame. The resulting transformation depends on the orient parameter.
For my case, passing orient='records'
, a list of dictionaries is returned. When dealing with lists, the complete memory required to store the list items, is reserved/allocated. As my dataframe can get rather large, this might lead to memory issues especially as the code might be executed on lower spec target systems.
I could certainly circumvent this issue by processing the dataframe chunk-wise and generate the list of dictionaries for each chunk which is then passed to the API. Furthermore, calling iter(df.to_dict(orient='records'))
would return the desired generator, but would not reduce the required memory footprint as the list is created intermediately.
Is there a way to directly return a generator expression from df.to_dict(orient='records')
instead of a list in order to reduce the memory footprint?
ANSWER
Answered 2022-Feb-25 at 22:32There is not a way to get a generator directly from to_dict(orient='records')
. However, it is possible to modify the to_dict
source code to be a generator instead of returning a list comprehension:
QUESTION
I've built this new ggplot2
geom layer I'm calling geom_triangles
(see https://github.com/ctesta01/ggtriangles/) that plots isosceles triangles given aesthetics including x, y, z
where z
is the height of the triangle and
the base of the isosceles triangle has midpoint (x,y) on the graph.
What I want is for the geom_triangles()
layer to automatically provide legend components for the height and width of the triangles, but I am not sure how to do that.
I understand based on this reference that I may need to adjust the draw_key
argument in the ggproto
StatTriangles
object, but I'm not sure how I would do that and can't seem to find examples online of how to do it. I've been looking at the source code in ggplot2
for the draw_key
functions, but I'm not sure how I would introduce multiple legend components (one for each of height and width) in a single draw_key
argument in the StatTriangles
ggproto
.
ANSWER
Answered 2022-Jan-30 at 18:08I think you might be slightly overcomplicating things. Ideally, you'd just want a single key drawing method for the whole layer. However, because you're using a Stat
to do the majority of calculations, this becomes hairy to implement. In my answer, I'm avoiding this.
Let's say I'd want to use a geom-only implementation of such a layer. I can make the following (simplified) class/constructor pair. Below, I haven't bothered width_scale
or height_scale
parameters, just for simplicity.
QUESTION
Let's say I've got a dataframe with multiple columns, some of which I want to transform. The column names define what transformation needs to be used.
...ANSWER
Answered 2021-Dec-19 at 11:52One way can be to use lapply:
QUESTION
I am a bit stuck, I have a working function that can be utilised using .apply()
, however, I cannot seem to get it to work with .assign()
. I'd like this to work with assign, so I can chain a number of transformations together.
Could anyone point me in the right direction to resolving the issue?
This works
...ANSWER
Answered 2021-Dec-14 at 17:39From the documentation of DataFrame.assign
:
DataFrame.assign(**kwargs)
(...)
Parameters **kwargs : dict of {str: callable or Series}
The column names are keywords. If the values are callable, they are computed on the DataFrame and assigned to the new columns. The callable must not change input DataFrame (though pandas doesn’t check it). If the values are not callable, (e.g. a Series, scalar, or array), they are simply assigned.
This means that in
QUESTION
I'm looking for a way to have all keys / values pair of a nested object.
(For the autocomplete of MongoDB dot notation key / value type)
...ANSWER
Answered 2021-Dec-02 at 09:30In order to achieve this goal we need to create permutation of all allowed paths. For example:
QUESTION
I was trying to find the source for a certain kind of inlining that happens in GHC, where a function that is passed as an argument to another function is inlined. For example, I may write a definition like the following (using my own List type to avoid rewrite rules):
...ANSWER
Answered 2021-Nov-25 at 10:34The optimization is called "call-pattern specialization" (a.k.a. SpecConstr) this specializes functions according to which arguments they are applied to. The optimization is described in the paper "Call-pattern specialisation for Haskell programs" by Simon Peyton Jones. The current implementation in GHC is different from what is described in that paper in two highly relevant ways:
- SpecConstr can apply to any call in the same module, not just recursive calls inside a single definition.
- SpecConstr can apply to functions as arguments, not just constructors. However, it doesn't work for lambdas, unless they have been floated out by full laziness.
Here is the relevant part of the core that is produced without this optimization, using -fno-spec-constr
, and with the -dsuppress-all -dsuppress-uniques -dno-typeable-binds
flags:
QUESTION
I have a complex nested dictionary structured like this:
...ANSWER
Answered 2021-Nov-05 at 09:13I was able to get about 25 % faster by combining the three processes.
QUESTION
I'm running the test
...ANSWER
Answered 2021-Sep-12 at 09:37To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
From the above suggestions, we can tell Jest not to parse ES modules in node_modules
.
In your jest.config.js
file, you can add the following lines. You can add any ES module you want to the array.
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